I can run Opera in my user account but It doesn't work in the guest account.
I first downloaded the .deb package from:
Installed with apt:
sudo apt install opera-stable_40.0.2308.62_i386.deb
Worked well but when someone tried to use the "guest account" it wasn't possible to run Opera.
They could see the icon but nothing happened when clicked on it. Trying to run Opera from terminal in "guest account" gives errors and produce "core".
Unistalled Opera to try another method of installation:
sudo apt purge opera-stable
Then I tried to install Opera with the method of adding the ppa:
sudo add-apt-repository 'deb https://deb.opera.com/opera-stable/ stable non-free'
wget -qO- https://deb.opera.com/archive.key | sudo apt-key add -
sudo apt-get update
sudo apt-get install opera-stable
It hasn't solved the problem.
Guests have still Epiphany and Firefox... (No Opera for them)
Thanks for your help.